The invention relates to tire curing molds of the split-mold type including a mold base, which can be placed on a tire curing platen of a tire curing press or can be part of a tire curing press, and a mold top which is movable relative to the mold base, in the direction of the mold axis, and which can be affixed to the press upper mold carrier of the tire curing press, or can be part of the press upper mold carrier. In the latter case, the lower mold portion includes a lower sidewall plate for forming the tire sidewall area, and a plurality of radially movable sectors carried on the mold base which, when the mold is closed, cooperate to form a ring the inner surface of which is formed representing the tire tread. The sectors are movable by hydraulic means or the like which is coupled to the sectors. The upper mold part defines an upper sidewall form for forming the other tire side wall. A closing ring, which depends from the upper mold part contains inner conical or planar shaped surfaces which converge inwardly towards the top and which interact with the respective opposing surfaces of the sectors during closing of the mold to drive the sectors to their use position and to maintain the sectors at their use position during curing of the tire.
In principle, it is advantageous to keep the outer diameter of a tire curing mold as small as possible. The smaller the diameter and, thus the bulk of a mold, the less energy is required for the curing process. Also, the size of a tire curing press to be built into the mold is dependent on the outer diameter of the mold. The smaller the outer diameter of the mold, the smaller the tire curing press must be. The outer diameter of a mold is determined mainly by the size of the tire to be built, but also by the mold's construction. If, for example, the drive means for the radial movement of the sectors are located at the bottom of the mold, the outer diameter would be smaller than would be the case where the drive means were located on the radial outside of the sectors.
One known tire curing mold is integrated into a tire curing press. The slide arrangement for the sectors is located below the press platen. This slide arrangement has relatively long bent levers for moving the sectors. Together, these bent levers are moved through axial movement of a festoon. This slide arrangement requires no room extending over the minimum outside diameter of the mold prescribed anyway. However, a space of a relatively large height is required below the mold bladder/cavity, because the known construction is suitable only for a mold built into a press. The closing ring of this known mold has a conical inside surface, the height of which is only slightly less than the height of the sectors. The outer surfaces of the sectors are conical so that the diameter of the ring formed by the sectors increases from top to bottom.
To receive a cured tire, the sectors must be moved outward so far that the mold projections, which form the tire profile, are drawn out of the profile and that the inside diameter of the upper rim of the sector ring is equal to or slightly larger than the outer diameter of the tire.